Friction clutch



July 8, 1924. 1,500,971

. w. WALLACE IFRI TI QN CLUTCH File d April 30. 1924 2 Sheets-Sheet; 1

WA MLL WALLALK &

July 8 w. WALLACE FRICTION CLUTCH Filed April 30, 1924 2 Shets-Sheet 2 fivenfio v WILLIAMWAFLALE l v fill!!! Patented July 8, I924.

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WIL AM WALLACE, or OLDHAM, ENGLAND.

FRICTION CLUTCH.

Application filed April 30, 1924. Serial No. 710,164.

To all whom it may concern: 7

Be it known that I, WILLIAM WALLACE, a British subject, residing in 178 Frederick Street, Oldham, in the county of Lancaster, England, have invented certain new and useful Improvements Relating to Friction Clutches, of which the following is a specification. A

This invention relates to friction clutches and is particularly applicable to friction clutches for motor-car engines of that type in which the engaging surfaces, usually two series of metallic discs, are enclosed in a revolving casing containing fluidlubricant,' and in which the main 'presser spring acting through a presser plate normally causes the engagement of the frictional surfaces, and

in which disengagement is effected by retraction of the presser plate in opposition to the said spring; and the object of the invention is to provide means adapted auto matically to prevent the too sudden engagement of the friction surfaces such as takes place when the retracting pressure on the presser plate is released too rapidly say by unskilful operation ofthe clutch pedal.

'According to the inventiointhe resistance to displacement of anannular band of lubricant, forced by centrifugal action against the interior of the rotating clutch casing, is

utilized to ensurethe gradual and evenmovement of the parts which effect the engagement of the frictionalsurfaces.

In the ordinary construction of clutches of the type herein referred to, the presser plate, when released from the retracting ressure, is free to move under the influence of its actuat ng spring, into the engaging position, such movement not being resisted by the displacement of'the said band of lu bricant; but in carrying out my'invention the jointbetween the periphery o'fthis plate or of a plate adapted to move with it', and the interior of the clutch casing, is made sufiiciently fluid-tight to ensure the necessary and gradual resistance to displacement of the lubricant by the said movement;

where the interior of the casing is provided with-teeth to engage the one-set of friction plates, the presserplate is indented so that it fits the said teethj throughout the ;whole ofthe circumference, the comparative fluidtightness being sufficient to ensurethe "neces sary resistance todisplaqiement by leakage past these surfaces;* the contact surfaces may, however, be cyhndrical, and one of them may be a packing ring of leather or the like material. As the resistance to displacement depends upon the comparative fluld-tightness of the joint, this may be va-I lledtO give the desired resistance, definite and adjustable leakage passage-ways being 7 provided in some cases.

As the speed of rotation of the driven parts is usually decreased as the clutch en gages, the centrifugal force is reduced, and r the resistance to displacement of the band of lubricant, by increasin'gthe radial depth of the band thereof, decreases, so that the lubricant may in part be displaced by this radial movement, and the parts may be so proportioned that this'radial movement in creases the lubricating action.

I have illustrated my invention by way of.

example in the accompanying drawings, in which: i

Figs. 1 and 2 show a motor-car clutch of the preferred form, in which the comparatively fluid-tight joint is made directly between the periphery of the presser plate and the interior of the casing.

Fig. '1 being a side elevation in medial section, and, I Fig. 2 a fragmentaryend elevation in transverse section on the line II, II' of Fig; 1. Fig. 3 which shows a modification of the arrangement of Figs. land 2, is a fragmentary side elevation in medial sectionl Figs. 4', 5, 6 and 7 are diagrammatic views, similar to Fig. 3; Figs. 4 we show modifi cations in -which the comparatively fluid tight jointismade'between the casing and a packing ring carried by the presser plate; and F ig 7 shows the'packing ring fitted to one of'the frietion plates; v

Figs. 8 to 11 show th'e'preferred construction when the presser plate is fitted with a packing ring.

a Fig. 8 being side elevation'in medial plate with clutch. is hed by the "facin a to the engine fly-wheel which completely encloses'the interior of the casing. B is the driven element which takes the form of a boss rigidly secured to the driven shaft C, the free end of which shaft is journalled in the ball bearing 0 carried in the end plate a which maintains the bearing 0 and shaft G in concentric relationship with the driving element. The exterior of the boss B is provided with a series of teeth 6 which engage with theindented bores of the driveninetallic friction plates. The friction plates, which are not shown in Figs. 1 and 2, "may be plaindiscs of any suitable type arranged in the usual manner in :two alternately disposed groups, the one group engaging with thecasing A and being clear of the boss B,rand the otherengaging with the latter and being clear ofthe former; but we find that the well known Hele-Sh-aw T- shaped friction .plates as shown in Figs. 3 t0 8 are admirably suited for-use in connec tion with the present invention.

D is the presser plate mounted :on the sleeve dfwhichis provided with a liner d and is adapted to slide on the shaft C. The presser plate is, normally, pressed axially, by aspring E, so asto transmit through the frictional plates the necessary pressure to ensure their friction engagement to transmit the desired torque from driving to driven element. The-springE, in the con struction illustrated, islocated'in the spring box 6 which screws into a boss on the end of the casingand may therefore be initially adjusted to give the desired degree-ofcompression to the spring. To declutch, the pressure-plate is retracted by any convenient pedal controlled means.v In the example illustrated the pressure-plate sleeve d is provided at itsouter end with a non-rotational pedal-operated bushing (P which is journalled on the sleeve d by :the ball bearing d*. This bushing .is fitted with a pair of diametrally disposed pivot pins d with which the ends of a bow-shaped lever 62 (shown in chain dotted lines) engages, the lever being mounted on the pedal shaft d".

F is a coupling, keyed to the shaft C, by which the latter is coupled to the gear to be driven; f is a brake block the screwedbore of which fits the coupling F and which canbe adjusted axially relatively thereto. Ondeclutching the fibre disc f engages withthe rotationally fixed facing d of the bushing 65 and the frictional engagement serves to bring the shaft C to rest.

In the ordinary construction of clutches of the type described the periphery of the presser-plate'D does not fit the interior periphery of the clutch'casing A in such manner as :to make .a comparatively fluid-tight joint but according to the present :invention as applied tothe type of clutch described, the

indented peripheral surface (Z of the presser-plate D, and the toothed interior surface of the clutch casing A are sofitted together that whilst relative axial movement between these surfaces is permitted, the fit between them is sufficiently fiuidtight to retard the axial flow of oil between the-1n from one side of the presser-plate to the other, when, upon the release of the bushing (Z the spring E tends to push the presser-plate into contact with the friction plates, lVhen this action takes place, the casing is rotating and the oil. contained therein will, by virtue of centrifugal force, occupy an annular belt indicated by the dotted lines in Fig. 1 bounded by theouter parts of the interior of the clutch casing and by the cylindrical surface 00,00. movement of the resser-plate to the left (under the action of spring E when the bushing 03 is released) if there be no substantial leakage-of oil between the peripheral surfaces of the plate and the casing, must displace the oil on the left side .of the presser-plate'so as :to increase the radial dimension 3/ of the oil belt by an amount corresponding with the amount of :reduction of the axial dimension of the belt, and as such displacement must be made in opposition to the pressuredue to the centrifugal force acting on the oil, the said movement due to-the spring will be an easy and gradual one since it is controlled by the fluidjresistence, and the degree of *resistence may be adjusted, if necessary, by adjusting the extent of leakage past the peripheral sure faces'of the presser-plateand the casing, or by providing an adjustable leakage passage.

As stated, in the construction illustrated in Figs. 1 and 2, the toothed inner surface of theicasing and the corresponding surface d of the presser-plate are by machining made a sufficiently good fit to ensure the necessary-degreeof fluid tightness. In some cases, however, the periphery of the presserplate may be madeof truly cylindrical configuration as shown at d Fig. 3,.and'fit a corresponding cylindrical part a of the interior of thecasing A, in which case the degree of fluid-tightnessof the joint may be moreeasily determined; in such cases the rotation of the ,presserplate relatively to the casing'must be prevented,sayby attaching it to the end frictiondisc g In some cases the presser-plate D may be fitted with a packing ring (see Fig. 4C) of leather, fibre or'the like, the surface of the ring, which in Fig. 4. is cylindrical, fitting 'thecylindrical bore a ofthecasi'ng.

Or, as shown in Fig. .6, the :ring H and the periphery of the resser-plate may be shaped to fit the teeth a of the'casing, the packing ring being compressed by the :ring 7% riveted to the presser-plate. j v

In some cases the ring H (see Fig; -;7) may be attached to one of the friction discs Any 9 or several such rings may be fitted one to each of several friction discs.

Where there is much leakage past the packing ring it may be attached to the presser-plate so as to be axially movable relatively thereto, as shown in Fig. 5 where the ring II is attached to the presser-plate D by studs 72, When the presser-plate is drawn back, as shown in Fig. 5 any oil which may have escaped to the right past the ring H can find its way back through ports such as if which are covered by the face of the presser-plate D whenthe latter is pressing the friction plates together.

The preferred construction, when the presser-plate is fitted with a plain packing ring fitting a cylindrical part of the interior of the casing, is that shown in Figs. 8 to 11. In this modification the casing A is closed by an end cover plate a and the ball bearing 0 is carried on the bore of the opposite end a and the flange or of the driving shaft a is bolted to the said end a. Instead of teeth integral with the casing, to connect the driving friction discs 9 to the casing, a series of studs a attached to the casing, are provided for this purpose, and these studs pass through the presser-plate D and drive it, flow of oil through the holes in the presser-plate to take these studs being prevented by leather or the like packing rings (4 fitting the studs and being held in compression by the plates or, screwed to the presser-plate.

In this modification instead of a single central spring to actuate the presser-plate, as in Figs. 1 and 2, three springs located in spring-tubes 6 carried by the presserplate are employed for this purpose; the springs at one end bearing against leather washers c at the bottoms of the respective spring-tubes, the other ends of the springs bearing on adjustable nuts 6 carried on studs e attached to the casing A and passing through the spring tubes; access to these nuts being obtained by removal of the caps 6 c c I V The presser-plate sleeve is mounted on the shaft C by bushes d and is provided with a non-rotational pedal operated bushing oZ which is similar in construction and action to that described in reference. to Figs. 1 and 2.

The presser-plate is recessed, see d Figs. 10 and 1 1, to take the packing ring H, and the latter is held in place and compressed by a metal'ring h secured'to the presser ring by the screws or rivets 72/ The rings H and 72 are recessed to take the spring-tubes e".

In the drawings, the respective surfaces between which the joints are made, are shown in contact, as the degree of clearance necessary to give the desired retarding efiect is too small to be shown clearly.

Obviously the details of construction may be Varied to suit diiferent types of clutches.

Having now particularly described my invention I declare that what I claim and desireto secure by Letters Patent is:

1. A method of modifying the action of a clutch which includes the step of opposing the centrifugal force of a rotating body of lubricant by changing its bodily dimensions.

2. Incombination a clutch casing, a presser plate movable coaxially with and within said casing, clutch discs movable by said presser plate, and a packing means carried by a clutch disc and engaging the casing.

3. 'In combination, a clutch casing, a presser plate movable coaxially with and within said casing, clutch discs movable by. said presser plate, and a packing means carried by a clutch disc and engaging the casing,

said packing means being also attached. to the presser plate and movable relatively thereto.

In witness whereof I have hereunto set my hand in the presence of two subscribing witnesses.

WILLIAM WALLACE.

Witnesses 7 WILLIAM LENNON, I JOHN WILLIAM THOMAS. 

